Find the smallest prime which can be represented as sum of a prime and its reversal.
Clearly, if one wants to solve it at first glance
, - one would begin testing numbers of a 2?1
structure by choosing a prime one and then trying 2?1*1?2 -
if it's prime - stop. Solved.
No - continue with 2?7
Ok: 201 not a prime; 211+112=323 not a prime; 221+122=343 not a prime; 231 not a prime; 241+142= a prime number, smallest, ANSWER.
Conclusion - it always pays to try the "guessing process" at least for a while.